Physical and Chemical Properties in Diffusion of Bentonite and Micro/Macro Analysis

对于有毒物质的废物管理，迫切需要了解运输现象的真实物理和化学过程，并提高安全评估的可靠性，因为任何基于实验模型的传统方法都存在难以估计稳健性的问题。为了解决这一困难，我们从分子动力学(MD)模拟方法入手，了解水化蒙皂石粘土矿物的离子状态和扩散特性等基于分子的基本性质，并应用多尺度均匀化分析(HA)方法将微观性质扩展到宏观行为。在分子动力学模拟中，我们精确地模拟了粘土矿物附近阳离子和水的分子行为。在2002财年，计算了层间阳离子Cs和Ca的溶胀性质和扩散系数。2003财年对原子间势模型进行了改进，计算了几种层间阳离子的扩散系数。2004财年进一步完善了原子间相互作用势模型，使其溶胀和扩散特性更加逼真。然后计算了阳离子的配位数。2005财年，对高岭土的性质进行了计算。微观图像是表征膨润土微观/宏观行为的重要指标。2002财年，我们用激光共聚焦扫描显微镜(LSM)对膨润土的微观结构进行了观察。2003财年，基于MD获得的局部材料性质的知识和微观观察，我们用HA方法模拟了膨润土扩散实验的微观/宏观行为，包括粘土矿物边缘的微观吸附特性。2004财年，对包含微吸附的HA模型进行了改进。2005财年讨论了泥岩的微尺度特性。

For waste management of toxic materials it is keenly required to understand the true physical and chemical process of the transport phenomena and to improve reliability of the safety assessment, since any conventional methods based on experimental models involve difficulty to estimate the robustness. In order to solve this difficulty we start with the molecular dynamics (MD) simulation method for understanding the molecular-based fundamental properties such as an ionic state and diffusion characteristics of hydrated smectite clay minerals, and we extend the microscale properties to the macroscale behaviors by applying the multiscale homogenization analysis (HA) method.In the MD simulation we precisely simulated the molecular behaviors of cations and H_2O in the neighborhood of a clay mineral. In FY2002 the swelling property and diffusivity of interlayer cations, Cs and Ca, were calculated. In FY2003 the interatomic potential model was improved, and the diffusivity of several interlayer cations were calculated. In FY2004 the interatomic potential model was further improved, and the swelling and diffusive properties became more realistic. Then the coordination number of cations were calculated. In FY2005 properties of kaolinite were calculated.A microscopic image is important to specify micro/macro behavior of bentonite. In FY2002 we observed microstructures of bentonite by using a confocal laser scanning microscope (LSM). In FY2003 based on the knowledge of the local material properties obtained by MD and the microscopic observation we simulated the micro-/macro-behavior of diffusion experiments of the bentonite which included the microscale adsorption characteristics at the edges of clay minerals by using a HA method. In FY2004 the HA model including micro-sorption was improved. In FY2005 microscale properties of mudstone were discussed.